摘要
中国南方晚第三纪孢粉植物群的研究历来是第三纪孢粉研究中的一个薄弱环节。该文通过综合近20年来的研究进展,对本地区晚第三纪孢粉植物群的时空变化作了初步分析和归纳,并将中国南方晚第三纪孢粉植物群的纵向变化分成四个阶段,横向上划分为不同的植物区系。
With the accumulation of data, remarkable progress in the Neogene palynology of South Chinahas been made over the last twenty years. The present paper alms at making a comprehensive reviewof the palynofloristic changes in the Neogene of South China, in combination with some initial resultsmade by the present author. In the text, South China refers to the region beyond south of Kunlunshan Mts. , Qaidam Basin,Qinlingshan Mts. and the middle and lower reaches of the Yangtze River (fig. 1 ). The geological timescale mainly follows Cowie and Bassett's 1989 Global Stratigraphic Chart except for the lower bound- ary of the Quaternary. The Matsuyama/Gauss boundary is generally regarded as the lower boundaryof the Quaternary in China, i.e. , set the Matsuyama (3.4--2.43 Ma) in the Late Pliocene,which isfollowed in this paper. ary of the Quaternary. The Matsuyama/Gauss boundary is generally regarded as the lower boundaryof the Quaternary in China, i.e. , set the Matsuyama (3.4--2.43 Ma) in the Late Pliocene,which isfollowed in this paper. Ⅰ The pollen floras in the Neogene of South China became more complicated as compared with thosein the Paleogene. This is largely due to the gradual intensification of the latitudinal and topographicdifferentiation in the area. As floras in various regions developed separately, their regional featuresbecame more and more distinct. In addition, although variations in the climate cast less effect in theSouth than in the North, the climate was also divergent in different areas of South China because ofintensified topographic differentiation. As a whole, however,the development processes of the southern floras share a similar patternwith that of the northern ones. Within the process of plant evolution, the major developmental stagefor dicotyledonous herbs is mainly after the Middle Miocene, while some forms which ended or begantheir ranges also show a certain regularity. As to the external environment, major tectonic movementsin the Cenozoic are generally simultaneous, while the new developmental stage of floras often followsthose events. Meanwhile, changes in climate are also largely connected with the tectonic movementsbecause the reconstruction of climate zones generally keeps in step with those movements despite of theless climatic influence on the southern areas. Therefore, in case of any change taking place within aflora, it is difficult to distinguish the tectonic influence from the climatic influence. As to a warm pe-riod flora, a stable tectonic background and climate are preconditions for it to flourish. To sum up, the development of Neogene pollen floras in South China can be divided into fourmajor stages, which correspond to those revealed from North China, occurring in early EarlyMiocene, late Early Miocene-early Middle Miocene, Middle Miocene- Early Pliocene and LatePliocene respectively. The pollen floras of the first stage have a rather limited distribution, while thoseof the second stage have a wide distribution, reflecting the climatic optimum of the Neogene warmthunder a relatively stable tectonic background. The pollen floras of the third stage show a process of dis-tinct differentiation, corresponding to the then topographic changes and climatic fluctuation, thusmaking it difficult to compare the pollen floras in different regions. The pollen floras of the fourthstage can be clearly recognized in Xizang (Tibet) because of palaeomagnetic data, but it is generallynot easy to distinguish them in other places. Stage 1. In this stage the main features include a decreased amount of gymnospermous pollen as comparedwith that of the Late Oligocene; dominance of both evergreen Quercoidites and pollen of Cyclobalanopsisor Uupuliferoipollenites; a few Chenopodiaceae pollen and a small amount of other angiospermousherbaceous pollen sand more monoletes than triletes among the spores. These palynologicat assemblagesare mainly found in the middle part of the Toupi Group, Toupi Basin; the Xiayang Formation ofBeibuwan Depression and Leiqiong Area; and the lower part of the Dingqing Formation, Lun
出处
《微体古生物学报》
CSCD
北大核心
1992年第1期81-95,共15页
Acta Micropalaeontologica Sinica
关键词
孢粉植物群
植物区系
晚第三纪
palynofloras
floristic regions
Neogene
South China
